


-7^ 



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TA4^4 
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LECTURE 



ON THE 



Preservation of Wood 



AS 



Adapted to Shipbuilding, 



GIVEN BEFORE THE 



BY 

- CHARLES E. MUjS^ROE, 

PROFESSOR OF CHEMISTRY U. S. N. A. 



1877. 



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PRESS OF / 
THE OLAREMONT MANUFAP" ..ING COMPANY, 
CLAREMO^"^ N. H, 



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THE RECORD 

OF THE 

UmTED States Nayal Institute. 

Tol. III. 1877. No. 5, 

U.S. NAVAL ACADEMY, ANNAPOLIS, 

June 14th, 1877. 

Commander W. T. Sampson, U. S. N., in the Chair. 



PEESERVATION OF WOOD. 
By Prof. Chas. E. Munroe, U. S. N. A. 



Mr. Chairman, Gentlemen^ 

Wherever life exists we find a constant struggle for its mainten- 
ance. In every animal and vegetable substance, so soon as the vital 
force ceases to act, we se^ that there is at once a tendency toward the 
resolution of the atoms of the highly organized structure into simpler 
compounds. All nature seems to lend its aid to effect this change. 
The chemical affinities of the constituent substances encourage it, the 
lower forms of life assist it, and the combined influence of air, moisture 
and heat complete the change. Everywhere these forces are active 
and decay and destruction threatens. 

All of the products of life which we employ either for food or cloth- 
ing or for constructing our habitations, our ships, or our tools are ex- 
posed to this danger ; and one of the most important industrial prob- 
lems, which man has had to meet, has been the protection of these sub- 
stances from decay. 

It is my intention to-night to confine myself to an examination of 
the methods proposed for the preservation of one of these substances, 
wood, and especially as it is employed in ship-building. Though it 
may seem unnecessary to you that I should give any statistics to show 
the great value of employing some means for attaining this result, yet 



it will I believe impress the importance of it more strongly upon our 
minds if we give a moment to their consideration. 

The first fact which attracts our attention is the rapid destruction of 
our forests which is diminishing the supply and increasing the cost of 
lumber. While, for instance, a single acre of pine land yields on an 
average only six thousand feet of timber, billions of feet are annually 
sold in the United States. In 1855 lumber sold for about $18 per M.; 
in 1860, for 124; and in 1865 for $45, (Hunt's Merchant's Mag. 
Feb. '66, p. 106). » Excellent authority states that in New England 
the cost of oak, ash and hickory has doubled during the past twenty 
years, being now $ 50 per M., to $ 25 then, and if the demand were as 
great as ten years ago it would be difficult to supply it. Certainly 
prudence demands a less rapid expenditure. 

But when we come to estimate the loss, which results from decay, the 
necessity for preservation becomes still more apparent. It was calcu- 
lated in 1866, that the loss by the decay of sleepers on American Rail- 
roads, amounted annually to 1 1056 pr. mile, and that if they were pre- 
served by cupric sulphate at a light expense there would be an annual 
saving of over $ 4,000,000, (Lewis) and if we included bridges and all 
the wooden parts of railways subject to decay, it is stated that 
120,000,000 would be saved annually, by impregnating them with 
coal tar (Robbins p. 67). Processes have been devised by which the 
durability of many kinds of wood can be doubled; hence if we consider 
how much timber is employed in the United States alone, in buildings, 
bridges, fences, ships, carriages and machines, we can readily see that 
a great saving would be effected, that our wealth would be increased, 
and that a large part of the labor, which is now employed in making 
good the losses from decay, could be used in production. 

It is more to our purpose, however, and it was my desire, to collect 
some statistics concerning the decay of ships ; but such as I have ob- 
tained are quite meagre and unsatisfactory. 

In 1833 Mr. Edye, (Calculations relating to the Equipment of Ships 
by John Edye, London), stated that the quantity of wood required an- 
nually to keep the five hundred and seventy four ships of the British Navy 
seaworthy was one hundred and twenty five thousand loads, while only 
one million loads was required to build them — twelve and one half per 
cent. Mr. Wm. Chapman, (Preservation of Timber from premature 
decay, &c., by Wm. Chapman), gives several instances of the rapid de- 
cay of ships of the Royal Navy about the commencement of the pres- 
ent century. He mentions three ships of seventy four guns decayed in 



3 

five years, three of seventy four guns decayed ia four years, and one of 
one hundred guns decayed in six years. Pering, (Brief Enquiry into 
the causes of the Premature Decay), says that ships of war are useless 
in five or six years. And he estimates the average duration to be eight 
years, and that the cost of the hull alone of one of these ships was 
nearly £ 100,000. 

When we come to our own service we find that here also the loss by 
decay is enormous. Our live oak ships are exceptional, their average 
life being, probably, a half century, but I find from an examination of 
the data given by Emmons (p 23 and S6, et seq.,) that the average cost 
per ton per year for repairs, was $ 6.00 amounting in the case of a ves- 
sel like the Ohio to S 16,569.57. Up to 1850 the Ohio cost for repairs 
$ 471,673. * If now we estimate the loss upon the basis of actual sea 
service we find that the average cost per ton (O. T.,) per year of ser- 
vice was $ 16.19. The cost of repairs to the Ohio per year of service 
was over $ 89,000, and the United States, Potomac, Brandywine &c., 
average about $35,000 while the Constitution, which was an exception- 
ally good ship, cost over $ 15,000 per year of service.f 

To gather any information about our present Navy is more difficult, 
and we must wait for some one to record for it what Emmons has so 
thoroughly done for the Navy previous to 1850. Such as we do find 
however shows that of late the loss from decay is greater than before. 
We find vessels built of white oak costing from a quarter of a million 
to over a million dollars thoroughly useless in eight to ten years. In- 
deed this is a large estimate, for it is stated by some authorities that 
the average age of a white oak ship is six years. The difficulties met 
with in getting any certain knowledge on the,subject are best shown by 
the following extract from a letter from the late chief of the Bureau of 
Construction and Repairs, Chief Naval Constructor I. Hanscom. He 
says, " I believe you will only be able to obtain approximate data as to 
the relative durability of Live and White Oak, White and Yellow 
Pine timber, as it varies so much, caused by the difierence in quality 
and degree of preservation, either by stowage or by the use of chemi- 
cals, that the condition of the timber at the time of using it can hardly 
be known. Still the contrast in the durability of the timber used in 
the construction of the " Franklin " and that of the " Delaware " — the 
former in good condition at the present time (twenty three years), and 
the latter generally rotten in eight years, each costing nearly the same, 

* While the cost of building her was only $547,889. 
t See Appendix. 



V 



4 

(cost of Del. S 1,178,000) is so great that a general idea may be ob- 
tained by which to judge of the durability of timber used before and 
after thorough seasoning. I judge that the loss to the Government in 
using unseasoned timber during six years from 1861 was at least 
$ 20,000,000." 

Incomplete as these statistics are they give us a partial idea of the 
magnitude of the loss, which we sustain by decay, and they fully war- 
rant our devising means for arresting it. 

One of the chief difficulties which presents itself, when we resort to 
chemical processes to effect the preservation of wood, lies in its very 
complicated structure. Being the product of vital processes and also 
the individual in which these processes are taking place, a tree neces- 
sarily contains very many different chemical substances arranged in a 
complicated manner. It is to the character of the constituent substan- 
ces and the manner of their arrangement that ^vood owes the prop- 
erties which render it so well suited to the purposes to which it is 
applied. 

A brief description of the structure of a tree and the way in which it 
is formed will more clearly explain these difficulties. If we examine a 
section of the stem of a tree we observe that it consists ; 1st, of the pith 
or its remains, at the centre; 2nd, of the wood surrounding the pith; 
and, 3rd, of the bark. 

In Fig. 1 is represented a section both vertical and horizontal of a 
branch of a tree, two years old, as it appears in December. The por- 
tion included in the lines marked A is of the first year's growth; those 
marked B indicate the wood of the second year ; while those marked C 
inclose the three layers of bark ; D represents the pith of loose cellular 
tissue ; E represents the pith rays or silver grain of hard cellular tissue 
connecting the pith with the green or middle layer of bark, which 
consists wholly of cellular tissue ; F marks the outer or corky layer of 
the bark, which is composed of dry, dead cells, which are formed of con- 
secutive layers from the outer portion of the living green layer ; G is 
the green layer of cellular tissue ; H shows the liber or inner bark, 
made up of cellular tissue penetrated by long bast cells, arranged paral- 
lel with the axis of growth ; I represents the place of the cambium or 
growing layer of organizable material which descends from the leaves 
between the liber and the sap wood during the period of growth ; K is 
a woody fibre, which gives strength to the stem and through which the 
crude sap rises ; L indicates the vessels or ducts, with various mark- 
ings, such as dots, rings and spirals, which are formed most abundant- 




r G, HI 



r,^, /. 




i:t 







ly in the spring and usually contain no fluid. They convey gases and 
aqueous vapors, and it may be that a large proportion of all the water 
ascending from the roots to the leaves passes through them as vapor; M 
is the layer of spiral vessels or ducts, which always inclose the pith and 
in the young shoot extend into the leaves and unite them to the pith 
during its life, which ceases with the first season. 

Though the assertion has given rise to much discussion it seems now 
to be well determined that a circulatory system exists in vegetables. 
For convenience it is divided into the vascular circulation and the hor- 
izontal or cellular circulation. In the first the sap from the roots pass- 
es up through the woody fibre and the elaborated sap or cambium 
passes down between the liber and the sap wood. In the second the 
fluids pass between the pith and the bark. The food for the growth of 
the tree is secured by the roots and the leaves. The roots absorb wa- 
ter and the nitrogenous and mineral substances which the tree requires. 
The leaves store up carbon from the decomposition of carbonic acid in 
the numerous stomatae w^ilh which they are provided. From these va- 
rious substances the several constituents of the tree are formed and by 
the circulatory system they are conveyed to the part of the individual 
where they are to perform their functions. Thus we see that while the 
tree lives, in a healthy state, by means of its roots and leaves, it holds 
communion with the earth, water, and air, and that the fluids, juices 
and deposits depend for their movement upon the presence and action 
of these parts. When this communication is interrupted by drought 
or exhaustion of the soil, by the stripping of the bark or the felling 
of the tree, growth ceases. The circulation still continues however, but 
waste a of tissue begins, decomposition sets in, and the tree becomes 
the prey of fungoid growth. If however, after felling, we lop off* the 
top of the tree, the vascular circulation ceases, and, if we remove the 
bark, cellular circulation stops. If now the tree is exposed to dry air 
at a moderate temperature, all vital processes are arrested and the wood 
is for the while preserved. Especially is this so if the sap wood is 
cut away and the pith is laid open. 

From this sketch we realize how very complex the physical structure 
of the tree is. *A narration of but a portion of the constituent sub- 
stances will show that its chemical structure is still more diversified. In 
all plants we find woody fibre or cellulose, and this is covered with in- 
crusting substances formed from the decay of the cells. The following 
substances are also found in quantities varying with the season and the 
locality, the species and the age of the plant. They are the constit- 



6 

ueiits of the sap such as albumecoidal substaDces, starch, grape sugar 
cane sugar, gum, tannic acid, coloring matters, pectose, resins, and 
volatile oils and the ordinary mineral constituents of plants, &c. 

From the composition and structure of the healthy material our 
discussion naturally turns to the consideration of the manner in which 
the decay (Eremacausis) takes place and of the conditions most favor- 
able to its progress. When wood in a moist state is ex posed to air it 
undergoes decomposition; a species of fermentation is occasioned by 
the nitrogenized constituents, in consequence of which oxygen is ab- 
sorbed, carbonic dioxide and water are exhaled, and the wood crumbles 
down into a blackish brown vegetable mold called humus, ulmine or 
geine. This decay occurs most rapidly in young, spongy w^ood, which 
admits the air most freely and at the same time contains a proportion? 
ately larger quantity of the albuminous substa,nce, than the harder 
and older portions. The decomposition of these albuminous constituents 
favors the growth of lichens and fungi and encourages the ravages of 
insects, to which the albuminous portions in particular aiford nutri- 
ment. Pure woody fibre by itself, is only very slightly affected by the 
destructive influences of weather as we see in cotton, linen, paper and 
other materials, formed from nearly j)ure cellulose. The decay arises 
wholly from the presence of the substances in the wood that are foreign 
to the woody fibre, but are present iu the juices of the wood while 
growing, and consist chiefly of albuminous matter, which, when decaying? 
causes the destruction of the other constituents of the wood also. Since 
resinous woods resist the action of damp and moisture for a long time, 
they are quite lasting ; next in respect to durability follow such kinds 
of wood as are very hard and compact and contain some substance, 
which li:^e tannic acid, resists decay. 

The conditions which obtain then are these ; a limited supply of air, 
a moist atmosphere, and a moderate temperature. Change either of 
these conditions and decomposition ceases. You will recall that these 
conditions air, moisture and heat are the very same as were shown by 
our eminent associate, Dr. Gihon, to exercise so baneful an effect upon 
the health of those who live in ships. Remove the moist atmosphere 
and while the health of the inhabitants is benefited the destruction 
which assists in |)olluting the air is delayed. 

Mr. Finchau, formerly Principal Builder to Her Majesty's dockyard, 
at Chatham, tried an experiment to show that the presence of all these 
conditions was essential to decay. He bored a hole in a perfectly sound 
timber in an old oak ship. The admission of air to the central part of 



the wood, moisture and heat being already present, caused the hole to- 
be filled up in the course of twenty-four hours with mold which speed- 
ily became so compact as to admit of being withdrawn like a stick. 

Other cases may be cited of the remarkable freedom of wood from 
decay when any of these conditions are changed. For instance, when 
there was free circulation of air and an absence of moisture as in the 
roof of Westminister Hall we find well preserved wood over four hun- 
dred and fifty. years old (1866). The carvings in oak at Stirling Castle 
are also over three hundred years old (1866), and Scotch fir was found in 
good condition after three hundred years, and the trusses of the roof of 
the Basilica of St, Paul, Kome, sound and good after one thousand years. 
Instances of longevity where there was an absence of air, and the wood 
was submerged in water, are found such as the piles from the foundation 
of the old Savoy Palace perfectly sound after six hundred and fifty 
years, the piles from Old London Bridge perfectly sound after eight- 
hundred years, &c. 

Preservation. 

In accordance with these observations, Wagner, (Chem. Tech. p. 474, 
Am. ed.), divides the methods adopted for the preservation of wood as 
follows : 1. the elimination, as much as possible, of the water from the 
wood previously to its being employed ; 2. the elimination of the con- 
stituents of the sap ; 3. by keeping up a good circulation of air near 
the wood so as to prevent its suffocation as it is termed ; 4. by chemi- 
cal alteration of the constituents of the sap ; 5. by the gradual miner- 
alization of the wood and thus the elimination of the organic matter ; 
and to these may be added 6, by the use of antiseptic agents. 

The first of these is the most universally employed- method, i. e. by 
seaso'ning. As formerly carried on, the wood, carefully protected from 
sun and rain, was stored away for years. An active circulation of air 
was permitted and by the slow action of this air all the moisture was 
extracted from the wood. As the presence of moisture is essential to 
the fermentation of the albuminous and saccharine constituents of the 
sap this fermentation is thereby prevented. But beside the loss of in- 
terest on the capital invested and the time required for this result to be 
attained this method has other objections. If the timber is in the log 
it is liable to become rent, and if the pith is not bored out it is liable 
to decay at the heart before the moisture can be evaporated from it. If 
cut into lumber great care must be taken to prevent warping and crack- 
ing. Consequently various processes have been proposed for hastening 



8 

the drying, while yet it is so controlled that cracking and warping are 
avoided. Several of the processes of seasoning depend too upon the re- 
moval of the sap. We have water seasoning, seasoning by steaming 
and boiling, seasoning by smoke drying and stove drying, seasoning by 
scorching and charring, seasoning by extraction of sap, &c. Water sea- 
soning, which is effected by submerging the wood for some time in water, 
renders it brittle. Seasoning by steaming and boiling also diminishes 
the strength and elasticity of the wood, for at temperatures somewhat 
below the boiling point, that is at 140° F., the albumen is coagulated 
and this seals up some of the water or sap in the wood and thereby 
weakens the cohesion of the particles. The process of smoke drying 
answers quite well but the same result is more easily attained by the 
Bethell or Robbins process to be described farther on. Stove drying 
renders the wood quite hygroscopic and leaves the pores open. Scorch- 
ing and charring are only applicable to wood already thoroughly sea- 
soned. If green wood is treated in this way the outside only is pro- 
tected ; the sap is sealed up in the interior and ferments and then de- 
composes. It may be well to mention here that the same unfortunate 
result is brought about if the green wood is covered Avith a coat of paint. 
The protection is wholly superficial and is very deceptive. It is far 
better to leave the wood uncovered for then if there is a free circulation 
of dry air, the wood will gradually season as the sap is evaporated. 
Owing to the belief that paint or varnish will protect wood under any 
circumstances it is no unusual occurrence to find the painted wood work 
of old buildings completely rotted away while the adjacent naked parts 
are quite sound. But the preservative action induced by charring sea- 
soned wood is undoubted, for by the destructive distillation of the su- 
perficial layer various antiseptic agents are formed which find their way 
into the interior of the wood and the charcoal left upon the surface acts 
to destroy all fungoid germs which seek an entrance. This process has 
been long employed for preserving piles &c., and has been used in the 
Portuguese and French Navies. M. de Lapparent makes use of a gas 
blowpipe, the flame from which is allowed to play upon every part of 
the timber in succession. By this means the degree of torrefaction can 
be regulated at will. Instances of the eflaciency of this process are cit- 
ed as follows. Charred wood has been dug up which must have lain 
in the ground fifteen hundred years, and was then perfectly sound. At 
Herculaneum, after two thousand years, the charred wood was found to 
be whole and undiminished. The methods proposed for seasoning by 
the extraction of the saj) alone have been abandoned as impracticable. 



Processes depending on the Chemical alteration of the Sap. 

The first of these processes that went into general use was Kyan's 
process, patented in Enghmd in 1832, and soon after in this country. 
This process, called Kyaniziug, consisted in immersing the wood in a 
dilute solution of mercuric chloride (corrosive sublimate) until it was 
thoroughly saturated, or if time was an object, injecting the solution by 
pressure in a closed vessel from which the air was first partially ex- 
hausted. In England a solution of one kilo, of the salt to eighty to 
one hundred liters of water is employed for railway sleepers. They are 
laid in an open tank. In Baden they remain in the solution, when 
they are to be impregnated to a depth of 82 m. m., for four days, So 
to 150 m. m., for seven days, 150 to 180 m. m., for ten days, 180 to 240 
m. m., for fourteen days, 240 to 300 m. m., for eighteen days, the solu- 
tion consisting of one kilo, of salt to two hundred liters of water. 
When taken out the Avood is washed and dried. 

The use of the mercuric chloride depends upon the fact that it con- 
verts the albumen into an insoluble compound, while the salt itself be- 
comes reduced to the mercurous chloride. This process was extensive- 
ly adopted in England, and to some extent in this country. The ob- 
jections urged are that the salt employed is costly, that when open 
tanks are used the process is tedious, and when closed vessels are em- 
ployed the method is very costly, that the mechanics who shape the 
wood are liable to be poisoned by the salt, and that the bolts which 
hold it are liable to corrosion. But the process when faithfully ex- 
ecuted seems to efiectually arrest the rapid decay of timber in exposed 
situations. 

Zinc chloride has an effect upon wood somewhat similar to that of 
mercuric chloride while it is a much cheaper salt. In 1838, Sir Wm. 
Burnett was granted a patent for preserving wood by this material and 
the process was known as Burnettizing. A solution of one kilo, of zinc 
chloride to ninety liters of water is employed. The wood is placed 
on a car and run into a large, air-tight, cylinder of iron and the solu- 
tion is forced in under pressure. Although this method is not a sure 
preventive of decay the advantages which result from using it are more 
than sufficient to justify its application to most kinds of timber in com- 
mon use, and in situations favorable to rapid decay. It has also a dis- 
tinct effect in rendering wood less liable to warp and crack when placed 
in dry situations. It is open to the same objection as the mercuric chlo- 
ride that the salt will act upon the iron or copper fastenings. This 



10 

process has beea quite thoroughly triad in this country by Mr. J. B. 
Francis of Lowell, Mass., and its preservative power in many cases was 
quite well shown. Pieces of various woods treated by Burnett's pro- 
cess were partially buried in the ground side by side with unburnett- 
ized similar pieces of the same woods. They were kept there for over 
five years, and at the end of that time while the unprepared specimens 
were thoroughly decayed most of the burnettized ones were in good con- 
dition. Especially was this the case with birch, beech and poplar. 

In the same year in which Burnett secured his patent another patent 
was granted in England to Bethell for the use of the heavy oil of tar 
for impregnating wood. This material is obtained as one of the by- 
products in the manufacture of coal gas. Although its composition 
varies considerably it always contains carbolic aod cresylic acids, which 
are among our best known antiseptic agents together with various resi- 
nous, empyreurnatic, and asphalt forming substances. The perserva- 
tive influence of these substances is well known. 

Bethell placed the wood in an air tight cylinder (See Fig. 2) and first 
produced a vacuum, by which means the air and moisture were extract- 
ed from the wood. Then the liquid was forced in until a pressure of one 
h undred and fifty pounds to the square inch was obtained, and the pressure 
was continued until the wood was sufficiently saturated. This process 
was very successful, specimens which were treated in this way having 
remained unchanged when buried for over eleven years. Dr. Ure says 
of this process, "the effect produced is that of perfectly coagulating the 
albumen in the sap, thus preventing its putrefaction. For wood that 
will be much exposed to the weather, and alternately wet and dry the 
mere coagulation of the sap is not sufficient; for although the albumen 
contained in the sap of the wood is most liable and the first to putrefy, 
yet the ligneous fibre itself, after it has been deprived of all sap, will, 
when exposed in a warm, damp situation, rot and crumble into dust. 
To preserve wood, therefore, that will be much exposed to the weather, 
it is not only necessary that the sap should be coagulated, but that the 
fibres should be protected from moisture, which is effectually done by 
this process. 

The atmospheric action on wood thus prepared renders it tougher, 
and infinitely stronger. A post made of beech, or even of Scotch fir, is 
rendered more durable, and as strong as one made of the best oak, 
the bituminous mixture with which all its parts are filled acting as a 
cement to bind the fibres together in a close, tough mass, and the more 
porous the wood is, the more durable and tough it becomes, as it im- 



11 

bibes a greater quantity of the bituminous oil, which is proved by its 
increased weight. The materials which are injected preserve iron and 
other metals from corrosion ; and an iron bolt drivea into wood so sat- 
urated, remains perfectly sound and free from rust. It also resists the 
attack of insects ; and it has been proved by Mr. Pritchard, at Shore- 
ham Harbor, that the teredo navalis, or naval worm, will not 
touch it. " 

In this country a patent has been granted to Robbins* for an im- 
provement in Bethell's process. He employs the oil of tar and drives 
the sap from the wood. Then he forces the tar in, in the form of a 
vapor, in which condition it is claimed that it penetrates more deeply 
into the wood and in a shorter time. It is claimed also that the wood 
is cleaner than when prepared by Bethell's process. One side of the 
Vandalia was treated in this way and it is proposed to compare its 
durability with the wood of the other side, both being manifestly under 
similar conditions. 

The objections which have been urged against the use of coal tar com- 
pounds are that they impart a disagreeable odor to the wood ; that the 
wood is difficult to work, as it clogs the tools, and that it renders the 
wood more inflammable. 

One of the most interesting methods devised for introducing preserva- 
tive agents into the pores of wood is that suggested and applied by 
Boucherie. Deep cuts were made in the trunk of a living tree near 
the roots, a sort of tank built around them, and the tank filled with the, 
solution. (See Fig. 4.) Sometimes the tree, immediately after felling, was 
placed upright in the solution. In either case the solution was drawn 
up by the aspirative force of the tree, and penetrated even to the leaves. 
According to Hyett (Parnell's Chemistry) a poplar tree, ninety feet 
high, placed with its lower end in a solution of acetate (pyrolignite) 
of iron of specific gravity 1.056, absorbed about ten feet cubic in six days. 
Afterward the method was modified by applying a rubber cup to the 
larger end of the log as it lay on the ground with the top lopped off. 
Then the solution was allowed to flow from a hight, in order to exert 

* For form of apparatus see Fig. 3. 

Description of Fig. 3. 
A, represents a retort in which the coal tar, resin or oleaginous substan- 
ces or compounds are placed and subjected to the action of heat, B is the 
man-hole for reaching the interior. C the pipe with branches E E w^hich 
connects the retort with the wood chambers D. F discharge pipe for re- 
tort. H discharge pipe for vapors condensed in chambers. 



12 

pressure, into the cup. (See Fig. 5.) By this means the sap was forced 
out and the solution flowed in. When the solution began to issue from 
the opposite end the operation was completed. Boucherie tried va- 
rious substances but the one which he decided upon as the best 
was cupric sulphate. The solution used is one kilo, cupric sulphate to 
one hundred litres of water. 

The testimonials to the efficacy of cupric sulphate are quite numerous. 
In some of the German mines it has given batter results than zinc chlo- 
ride. ( Dingler's Poly. Jour. 1871, Vol. 202, p. 174 .) But on certain 
German railways where it had been employed to protect the sleepers 
it was found to attack the iron. It is said in defense of the process that 
if the wood is thoroughly dried after impregnation, the iron will not be 
acted upon. However this may be, in ships where copper fastenings 
are used there would be no action. In 1855, the jury of the French 
Exposition made an extremely favorable report upon Boucherie's pro- 
cess, asserting not only its yalue, but its superior cheapness over the 
plan of creosoting. (Jour. Frank. Inst. 1856, vol. 32, p. 1.) In 1848, 
about eighty thousand sleepers saturated with cupric sulphate together 
with some that were unprotected, were laid down on the Northern rail- 
way of France. In 1855 that is, nine years afterward, the prepared 
sleepers were as good as ever, the others having long been decayed and 
replaced by new ones. For preserving telegraph posts, the cupric sul- 
phate has been similarly efiective. The saving to the French lines 
alone, up to 1855, was estimated at two and a half millions of francs 
(Compte Rendus 1868, vol. 67 p. 713.) By the report of the commis- 
sion to the exposition at Vienna we learn that this process is still resort- 
ed to for this purpose and that telegraph posts are made to last 
from fifteen to twenty years. (Vol. II, L. 2, p. 18.) Examples of the 
preservative value of cupric sulphate could be easily multiplied, but 
one more will suffice. In 1868, Boucherie Jr. exhibited to the French 
Academy specimens of wood which had been prepared according to his 
father's process and exposed since 1847. These specimens were as 
sound, as elastic, and as strong as when new, and readily yielded the re- 
action of the copper they still retained. Here was a test of twenty 
years standing. 

The rationale of the action of cupric sulphate has been stated by Koe- 
nig. (Am. Jour. Sci. 2 series, Vol. XXXII, p. 274.) The action is first 
the union of cupric sulphate with the resinous and albuminous constitu- 
ents and next the dissolving of the albuminous compounds by the excess 
of the cupric sulphate solution. By long immersion it is said to be pos- 




r,g.4. 







13 

sible to remove all of the nitrogenized bodies. Resinous woods retain 
the most basic salt. 

The process is useful only for green wood, and best adapted to light, 
porous, easily perishable woods. 

Beside the substances mentioned a multitude of others have been 
suggested but they have generally been abandoned. Some have aimed 
to introduce solutions of different substances so that the interchange of 
their atoms shall take place in the pores of the wood and an insoluble 
deposit will be formed there. But the tendency is to som.e extent to 
petrify the wood and thus to destroy those characteristics which adapt 
wood to its uses. You can easily realize how useful a carpenter's tools 
would be in shaping stone. 

I will speak of but one other method and that you are all somewhat 
familiar with. It is the preservation of wood by salting. This method 
of treating ship frames is imperatively required by the lake under- 
writers in new vessels of the first class. The American Lloyds recom- 
mend it but do not make it an absolute condition. 

" The mode of salting is to fix stops of boards between the timbers of 
the frames about the height of the load line, and when the ceiling and 
planking are worked and the plank-sheer ready to go into place the 
spaces between the timbers are filled with salt. Near the end of the 
vessel the salt is sometimes put between the frames quite down to the 
dead wood. A vessel of five hundred tons will take one hundred bbls. 
of salt applied in the usual manner." (W. W. Bates Ag. Kept. 1866.) 

The use of salt depends upon the fact that it incrusts the timbers 
and prevents the fermentation from taking place at the surface, but if 
applied to unseasoned wood its action being only superficial it does not 
arrest the decomposition of the interior. It has been used by Boucherie 
as a substitute for cupric sulphate but it could not compare with it. The 
use of it is objected to because being a deliquescent salt it keeps the at- 
mosphere moist. Beside it is corrosive. For instance so long ago as " be- 
tween 1768 and 1773, the practice prevailed of saturating ships with 
salt; but this was found to cause a rapid corrosion of the iron fas- 
tenings and to fill the 'vessels between decks with a constant damp va- 
por." (T. A. Britton, p. 112.) 

As we examine the various processes which are in use we observe one 
fact, that they are all of them adapted only to light, porous, easily pen- 
etrated woods. Only the sap wood of oak and denser woods can be 
reached, but this is the part which is most liable to decay and most in 
need of a preservative agent. 



14 

The conclusion to which I have come then is the following. 

The preservative processes enable us to use an inferior quality of 
wood with great safety. When vessels must be built in great haste 
and of interior material, the wood should always be subjected to the 
action of a preservative agent. 

It would no doubt be advantageous to treat the hard varieties of 
wood after they have been thoroughly seasoned, for although the treat- 
ment would be only superficial, in thoroughly seasoned wood, this 
would be sufficient. Of the materials employed the use of cupric sul- 
phate appears to me to be the best applicable for ship timber as re- 
gards cost, inflammability, freedom from odor, corrosive properties, 
poisonous action, deliquescence, durability and ease of application. 



15 



APPENDIX. 



Table showing the cost of repairs per ton per year of life and per ton per 
year of sea service up to 1850 of vessels of the U. S. Navy. 





















i- 


.• . 






i 


S fcb 


1 






II 


c 


o 




11 




11 


% 

s 


11 

S3 


Cost. 




ll 




5 


"5 '-' 












Building 


Repairs 






02 


o. 


5,=s 












complete 
4:38,149 


to 1850. 


yrs. 


yrs. 


y.m.d. 


s, 


^^• 


Franklin, 


74 


2257 


1815 


1815 


27,487 


35 


1 


8,9,8 


.35 


1.38 


Colunibiis, 2 


74 


24S0 


1816 


1819 


426,930 


260,468 


31 


3 


8,1,20 


3..36 


12.97 


Ohio, 2 


74 


2757 


1817 


1820 


547,889 


471,673 


30 


3 


5,3,10 


5.70 


32.65 


North Carolina, 


74 


2633 


1818 


1820 


431,852 


369,176 


30 


2 


4,9,16 


3.07 


29.33 


Delaware, 


74 


2633 


1817 


1820 


543,368 


459,199 


30 


3 


6,9,2 


3.59 


25.31 


Independence, 2 


54 


2257 


1814 


1814 


421,810 


538,392 


36 


1 


7,5,26 


6.60 


31.89 


United States, 


44 


1607 


1796 


1797 


299.336 


658,106 


53 


1 


20,5,17 


7.73 


20.07 


Constitution, 


44 


1607 


1796 


1797 


302,719 


495,236 


53 


1 


32,0,24 


5.82 


9.61 


Potomac, 


44 


1726 


1819 


1821 


350.000 


390,244 


29 


2 


10.8.23 


7.80 


20.93 


Brandy wine. 


44 


1726 


1S21 


18^5 


399.217 


644,496 


25 


4 


17,4,9 


14.93 


21.58 


Columbia, 2 


44 


1726 


1S25 


1836 


336,891 


136,339 


14 


11 


6,5,12 


5.65 


12.25 


Congress, 4 


44 


1867 


1839 


1841 


399,088 


122,631 


9 


2 


6,1,2 


7.39 


10.86 


Cumberland, 


44 


1726 


1825 


1842 


357,475 


114,802 


8 


17 


4,10,21 


8.31 


13..5d 


Savannah, 


44 


1726 


1820 


18+2 


400,739 


78,260 


8 


22 


4,7,27 


5.67 


9.86 


Raritan, 


44 


1726 


1820 


1843 


406,087 


81,663 


7 


23 


4,4,6 


6.76 


10.88 


Constellation, 


36 


1778 


1796 


1797 


314.212 


400.982 


53 


1 


22,5,17 


5.92 


13.97 


Macedonian, 2 


36 


1341 


1832 


1836 


258,872 


67,135 


14 


4 


6,2,7 


3.58 


8.15 


Average cost, 




















$6.02 


$16.19 



The first nine columns are compiled from Emmons' Statistical His- 
tory. The last two are added by me. 

Authorities. 
Physiology of Circulation — J. B. Pettigrew. 
Circulation of Sap in Plants — W. S. Clark. 
Wood— Watts Diet. Chemistry, Vol. V. p. 1044. 
Treatise on Dry Rot in Timber — T. A. Britton. 
Ship Timber in U. S.— TF. W. Bates, Ag. RepH. 1866,;?. 473. 
Eremacausis — Watts Diet. Chem. Vol. II., fig. 497. 
Decay of Wood Fibre — Miller's Organic Chemistry, p. 139. 
Preservation of Wood — " " " " 

Preservation of Wood — Wag?ier's Chem. Tech. p. 472. 
Preservation of Wood in Damp and Wet Situations — H. W. Lewis. 
Jour. Frank. Inst.— FoZ. L. II. p. 217. 
Decomposition of Organic Bodies, Omelin Vol. VII, p. 90. 
Cellulose, Gmelin Vol. XV, p. 123. 
Wood, Gmelin Vol. XV, p. 149. 

Burnettizing— p/)A. J. B. Francis, C. E. Lowell, Mass. 1859. 
Preservation of Wood— i?e/;i. to City of Boston 1873, F. W. Clarke. 



16 

Thilmany Process— i*/. A. Wood Pres. Co. Cleveland, Ohio. 

The Robbins Process for Rendering Wood Imperishable — Nat. Pat. Wood 
Pres. Co 1867. 

Statistical History of the Navy of the U. S. from 1775 to 1853—6?/ Lt. Geo. 
F. Emmons U. S. N. Wash. 1853. 

Pelonze et Fremy Traili de Chimie — Tome. IV, p. 776, et Seq. 

Conservirng des Holzes — Zwick Chem. Tech. p. 906. ^ 

First Forms of Vegetation — Hugh Macmillan. 



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